<p>A telecommunications apparatus 10 includes a sub-rack unit 15 and a plurality of plug-in units inserted from a front side of the sub-rack unit 15 in a Y1 direction and mounted in the sub-rack unit 15. The plug-in unit 16 includes a plug-in unit main body and an aluminum case 41 that covers so as to envelope the plug-in unit main body. An intermediate guide rail member 22 is inserted from the front of the sub-rack unit 15 and mounted by. tightening a lock bolt member similarly inserted from the front of the sub-rack unit 13.</p>
